In a case of forming a film on a wafer, if the film remains at a bevel (end portion) of the wafer, the film remaining at the bevel may become a dust source. An example of such a film is an amorphous carbon film formed by plasma enhanced chemical vapor deposition (PECVD). In some cases, the film is formed on the wafer in a state that the bevel is covered with a cover ring in order to prevent the film from being formed at the bevel. This enables the film to be formed on a surface of the wafer excluding the bevel. This is referred to as mask deposition. In these cases, when the wafer moves on a stage, there may be a problem that a positional relation between the bevel and the cover ring becomes unstable and therefore a position of the mask deposition becomes unstable.
In some cases, after the film is formed on the surface of the wafer including the bevel, the film is removed from the bevel in a state that a portion excluding the bevel is covered with an upper cover. This is referred to as bevel etching. According to the bevel etching, the film can be formed on the surface of the wafer excluding the bevel as similar to the mask deposition. In these cases, when the wafer moves on a stage, there may be a problem that a positional relation between the bevel and the upper cover becomes unstable and therefore a position of the bevel etching becomes unstable.